[ RadSafe ] Instruments to certify exporting equipment clean

[Thompson, Dewey L]

It would not be worth much for Sr-90/Y-90, as these are beta particle decay only. The sodium iodide crystal is quite efficient for photons, but unresponsive to beta.  The natural background on the NaI crystal would likely mask any Bremmstrahlung photons, unless you were using a really good shield. But why are you concerned about pure Sr/Y?  The original question was concerning screening for contaminants from Fukushima - the stated instrument would be perfect for the requested service - screening for gross contaminants from a reactor release (which will have photon). If you wanted to screen for Sr/Y, couple a thin window Geiger Tube and frisk.  

Dewey
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----- Original Message -----
From: radsafe-bounces at health.phys.iit.edu <radsafe-bounces at health.phys.iit.edu>
To: radsafe at health.phys.iit.edu <radsafe at health.phys.iit.edu>
Sent: Sun Apr 24 17:54:21 2011
Subject: Re: [ RadSafe ] Instruments to certify exporting equipment clean

How does this handle Strontium 90?

On 4/21/2011 9:38 AM, Robert J Gunter wrote:
> Greetings Peter et al,
>
>
> My company has supplied instruments and am working on a procedure for
> exactly this purpose.  Basically we have recommended a Ludlum Model 2221
> paired with a Ludlum Model 44-10 NaI probe.  This meter and probe
> combination is very capable of assessing natural background radiation.  Of
> course the background can change based on what you may be assessing.  For
> example, if you are shipping KCl, the Postassium (K) has a relatively high
> background due to naturally occurring K-40 isotope.  So you would want to
> have an unimpacted (pre-release) sample to use as your background if you are
> assessing something that has a relatively high concentration of naturally
> occurring radioactive material.
>
>
> We are nearly out of 44-10 probes but can get new ones.  We have a large
> number of the Ludlum Model 2221 meters for $1250 each (these are used but
> fully functional, Ludlum Instruments sells them new for double that price).
> We sell 44-10's for $560 and have two left.  Ludlum charges $1036 each for
> them.  We also sell the cable to connect the two for $30 each.  The
> advantage of the Ludlum Model 2221 is it has both a scaler and a ratemeter
> function.   This lets you document your daily background with a timed count.
> You can use this as a reference for counting your samples.  We tell our
> clients to assess further if the reading is 2X background.  This is
> basically a quick screening method that does not quantify anything.  We
> suppose that you will not likely find much and if you do, you would perform
> a more detailed analysis to determine if it is safe to ship the product.
> The NaI detector is far more sensitive when applied directly to the drum or
> container than any Ports radiation monitor is likely to be.
>
>
> The NaI probe is very sensitive and appropriate for what you are looking to
> assess (Mixed fission products).
>
>
> Yours,
>
> Rob
>
>
>
> Robert J. Gunter, MSc, CHP
>
> CHP Consultants/CHP Dosimetry
>
> www.chpconsultants.com
>
> www.chpdosimetry.com
>
> Toll Free: (888) 766-4833
>
> Fax:  (866) 491-9913
>
> Cel:  (865) 387-0028
>
> rjgunter at chpconsultants.com
>
>
>
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